Read about it!
Read the text below, look at the cloud video again, then answer the questions on the next page.
Clouds are visible collections of water in the air. Some clouds produce precipitation that falls to Earth in the form of rain, snow, sleet or hail. Other clouds simply appear as decorative figures in the sky.
Two ingredients are needed to form clouds: water vapor and particles in the air such as dust or sea spray. If the air is saturated with water, the water vapor can condense into droplets or be deposited as ice crystals around the particles. A collection of billions of these tiny droplets or ice crystals forms a cloud.
Clouds shift and change shape because of air movement. They dissipate, or seem to disappear, as the water droplets evaporate or move apart from each other. Winds also carry clouds across the sky. Because different levels of the atmosphere have different winds, it is possible to see clouds that are at different levels moving at different speeds.
Observe Clouds
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
